Rotary power tool with centrifugal coupling means

ABSTRACT

This invention pertains to a rotary impact power tool, such as a wrench, and novel centrifugal coupling means therefor, wherein a motor drives a cage member which mounts an impact element between an outside positioned hammer member and an inside positioned output shaft having an impact-receiving jaw. Centrifugal means mounted between the cage member and the hammer member is operative periodically to force the hammer member ahead of the cage member to cause an impact blow.

United States Patent 1 Maurer ROTARY POWER TOOL WITH CENTRIFUGAL COUPLING MEANS [11] 3,734,205 1 May 22, 1973 3,552,499 l/l971 Maurer ..l73/93.5

Primary Examiner-James A. Leppink Attorney-Eber J. Hyde [57] ABSTRACT This invention pertains to a rotary impact power tool, such as a wrench, and novel centrifugal coupling means therefor, wherein a motor drives a cage member which mounts an impact element between an outside positioned hammer member and an inside positioned output shaft having an impact-receiving jaw. Centrifugal means mounted between the cage member and the hammer member is operative periodically to force the hammer member ahead of the cage member to cause an impact blow.

6 Claims, 5 Drawing Figures PATENTEU W 2 3 INVENTOR.

SPENCER B. MAURER ATTORNEY ROTARY POWER TOOL WITH CENTRIFUGAL COUPLING MEANS OBJECTS An object of the present invention is to provide an impact tool having centrifugal coupling means with very few parts, and wherein the parts are easily and in expensively formed, resulting in a low-cost, reliable, durable tool.

Another object of the invention is to provide an impact wrench which operates by centrifugal force to couple a hammer to an anvil at the proper time, and which is capable of efficient operation at high torque as well as at low torque.

Still another object of the invention is to provide an coupling mechanism whose design avoids sharp reentrant angles on the hammer and anvil to eliminate high stress concentrations which lead to failure of hammer and anvil parts.

A further object of the invention is to provide an impact wrench wherein a plurality of coplanar impact elements strike simultaneous impact blows on a centrally located output shaft creating balanced torsional impulses on the output shaft; and wherein the rotation of the hammer between blows may be less than one, one, or more than one revolution as determined by the design of the centrifugal coupling.

For a better understanding of the present invention, reference is made to the following description, taken in conjunction with the drawings and claims.

With reference to the drawings:

FIG. 1 is a side view of a tool with the forward coupling and clutch portions shown in longitudinal section, as along lines A-A and BB FIGS. 2 and 4.

FIG. 2 is a transverse section taken along line A-A of FIG. 1, showing the coupling portion of the tool in its impact position.

FIG. 3 is a transverse section taken along line A-A of FIG. 1, showing the coupling portion of the tool in its direct drive position.

FIG. 4 is a transverse section taken along line B-B of FIG. 1, showing the clutch portionof the tool in its impact position.

FIG. 5 is a transverse section taken along line B--B of FIG. 1, showing the clutch portion of the tool in its disengaged position.

An aspect of the present invention lies in the provision of an inexpensive, reliable, durable rotary power impact tool such as an air driven impact wrench, wherein a motor is mounted within a housing, and an output shaft is also mounted on the housing for rotary power output. An impact receiving jaw is radially disposed on the periphery of the output shaft. A cage member is driven by the motor andmounts an elongated impact element adjacent to the output shaft near the impact receiving jaw with its axis parallel to the axis of the output shaft and radially displaced therefrom to rotate in an orbit about the output shaft. A ring-like hammer member surrounds the orbit of the impact ele ment, and means mount the hammer member in the housing for rotary motion essentially in unison with the impact element, but the hammer member is capable of limited relative rotary motion in respect to the impact element. Centrifugal means is mounted between the cage member and the hammer member and is operative without applying torque on the output shaft periodi- .15 air driven impact tool having a centrifugally operated I cally to force the hammer member ahead of the cage member to cause the impact element to move radially inwardly into the path of the impact receiving jaw and transmit an impact blow from the hammer transversely through the impact element to the impact receiving aw.

With reference to FIG. 1 there is shown a housing 10 within which is contained a motor (not shown in detail) having a drive shaft 11. The motor with its on-off and forward-reverse controls are well known in the art. The drive shaft 11 has a male splined end 12 which is in rotary driving engagement with a female splined end 13 of a cage member 14, thereby to cause the cage member 14 to rotate in unison with the motor drive shaft 1 1. A bearing 15 mounts the drive shaft 11 in the housing 10.

An output shaft 16 is mounted by a sleeve bearing 17 in the forward end of the housing 10, and it extends from outside the housing to a location inside the housing, adjacent to and surrounding the end of the motor drive shaft 11. The output shaft 16 includes an impact receiving jaw 23 having a forward direction impact face 18 and a reverse direction impact face 30, and the jaw 23 is radially disposed on the periphery of the output shaft 16, as shown in FIGS. 4 and 5.

The cage member 14 is essentially cylindrical and is comprised of two main portions; the coupling portion shown at section line A-A in FIG. 1, (shown at impact in FIG. 2 and at direct drive in FIG. 3); and the clutch portion shown at section line B-B in FIG. 1 (shown at impact in FIG. 4 and at disengage in FIG. 5).

As shown in FIGS. 1, 2, and 3, the coupling portion of the cage member 14 surrounds the motor shaft 11 and is directly driven through splines 12,13 on the shaft 11 and on the cage member 14, respectively, and the clutch portion of thecage member extends forward and portion 14' mounts around shoulder 16' of the output shaft 16. O ring member 22 retains the hammer member 25 in position on the cage member 14. The cage member 14 has a plurality of longitudinally extending pockets 19 in its outside surface at the coupling portion, which pockets extend radially inwardly toward the longitudinal axis of the tool. As shown there are four equi-spaced pockets, though only two could be utilized. In each of the pockets 19 there is positioned a centrifugal weight roller 21 which is free to move slightly in a radial direction in its "pocket 19.

Around the cage 14 and the centrifugal rollers 21 is a hammer member 25, the internal bore of which is formed of a plurality of forward direction cam faces 38 and reverse direction cam faces 38', there being one cam face, (forward and reverse) for each centrifugal roller 21. As shown in FIG. 3, when the centrifugal roller 21 is fully within the pocket 19 its radially outward surface does not clear a land 39 on the hammer 25 between cam faces 38and 38'. In this position the motor driven shaft 11 directly drives the cage 14 through splines 12,13, and the cage member 14 drives the hammer 25 forward through the plurality of centrifugal rollers 21, as shown in FIG. 3. This is the direct drive position of the coupling portion of the tool.

During acceleration of the entire mechanism, centrifugal force builds up on each of the centrifugal weight rollers 21. Each roller is in engagement with a cam face 38 on the inside diameter of the hammer 25, and the build-up of the centrifugal force causes the hammer 25 to move slightly ahead of the cage member 14 and its rollers 21 to the position shown in FIG.2, ready for impacting to start.

FIG. shows the clutch section in its disengaged condition corresponding to the direct drive position of the coupling portion shown in FIG. 3. Output shaft 16 is located on the longitudinal axis of the tool and is surrounded by an extension of the cage member 14, which in turn is surrounded by a massive portion of the hammer 25. The cage member 14 has two slots 20 which extend radially through it, and in each of the slots 20 is mounted an impact roller element 31 in position such that it can engage, simultaneously, the hammer member and the forward impact face 18 of the impact receiving jaw 23, as shown in FIG. 4 at the instant of impact. The inside diameter of the hammer member 25 (at section B-B) has two axial slots 32 for forward tool operation, and two axial slots 33 for reverse operation.

During forward operation of the tool, with the coupling portion in the direct drive position shown in FIG. 3, the clutch is in its disengaged condition shown in FIG. 5, with the impact elements 31 out of engagement with the impact receiving jaws 18. As previously explained, the cage 14 and its centrifugal roller means 21 are driving the hammer member 25 forward, picking up speed, and at the same time, by centrifugal force thrusting the centrifugal rollers 21 outwardly to cause the hammer member 25 to advance slightly ahead of the cage member 14. With reference to FIG. 5, it will be seen that when hammer member 25 moves slightly ahead of cage member 14, the face 34 of slot 32 forces the impact element 31 radially inwardly so that it can contact the forward impact face 18 of the anvil 23, as shown in FIG. 4. At this position impact element 31 is in solid engagement with both the face 34 of the hammer 25 and the forward impact face 18 of the impact receiving jaw 23, and a powerful blow is transmitted directly through the impact elements 31. As shown, it is preferable to have two, 180 spaced apart impact elements 31, and impact receiving jaws 23 to strike a balanced blow.

After the blow has been struck and centrifugal force and kinetic energy have been dissipated, the centrifugal rollers 21 are thrust back into their pockets as the cage member 14 advances slightly ahead of the hammer 25. This causes the clutch end of the tool to move from its impact position shown in FIG. 4 to its disengaged position shown in FIG. 5, ready for another impact cycle.

Reverse action of the tool is similar to the aforedescribed forward action, but with the motor shaft 11 moving in the reverse direction. The centrifugal weight rollers 21 operate in slots 19 as in the forward direction but in conjunction with the reverse cam faces 38' on the inside of the hammer member 25. During the reverse operation of the tool reverse impact faces on the impact receiving jaw 23 cooperate with impact elements 31 to transmit the reverse blow from the hammer member 25 to impact jaw 23 on the output shaft 16.

While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is aimed, therefore, in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

l. A rotary impact tool comprising, in combination:

a housing, a motor mounted in said housing,

an output shaft mounted on said housing for rotation and including an impact receiving jaw generally radially disposed on its periphery,

an elongated impact element,

a cage member driven by said motor and mounting said impact element adjacent to the output shaft in the vicinity of the impact receiving jaw with its axis parallel to the axis of the output shaft and radially displaced therefrom to rotate in an orbit-like path about the output shaft,

a ring-like hammer member surrounding the orbit of said impact element,

means mounting said hammer member in said housing for rotary motion essentially in unison with said impact element but being capable of limited relative rotary motion in respect thereto,

and centrifugal means mounted between said cage member and said hammer member operative periodically to force the hammer member ahead of the cage member to cause said impact element to move radially inward into the path of said impact receiving jaw in position to contact said impact receiving jaw and transmit an impact blow from said hammer member transversely through said impact element to said impact receiving jaw.

2. A rotary impact tool comprising, in combination:

a housing, a motor mounted in said housing,

output shaft means mounted on said housing for rotation and including an impact receiving jaw radially disposed on its periphery,

a generally cylindrical roller impact element,

a cage member driven by said motor mounting said roller impact element adjacent to the impact receiving jaw with its axis parallel to the axis of the output shaft and radially displaced therefrom to rotate in an orbit about the output shaft,

a ring-like hammer member surrounding the orbit of said roller impact element, means mounting said hammer member in said housing for rotary motion essentially in unison with said roller impact element but being capable of limited relative motion in respect thereto,

and centrifugal means mounted in and driven by said cage member periodically to force said hammer member forward ahead of the cage member without applying torque to the anvil to cause said impact element to move radially inward to contact said impact receiving jaw and transmit an impact blow from said hammer member transversely through said impact element to said impact receiving jaw.

3. A rotary impact tool, comprising, in combination:

a housing,

a motor having a motor drive shaft mounted in said housing,

a centrally located output shaft including an impact receiving aw,

means rotatably mounting said output shaft in said housing,

a cage member having slot means therein,

means mounting said cage member around said output shaft at the location of said impact receiving aw,

means connecting said motor drive shaft to said cage member to rotate said cage member as said motor and motor drive shaft rotate,

a ring-like hammer member having longitudinal groove means in its bore,

means co-axially mounting said hammer around said cage member and said output shaft for rotation with and in respect to said cage member and said output shaft,

generally cylindrical roller impact element mounted in said slot means in said cage member and extending radially through said slot means from said output shaft into said groove in said hammer member and with its axis parallel to the axis of said output shaft, the roller impact element allowing limited relative rotary motion between said cage member and said hammer member, and centrifugal means mounted between said cage member and said hammer member operative periodically during rotation to cause said hammer member to rotate forward ahead of said cage member, thereby to force said roller impact element radially inward into the annular path of said impact receiving jaw to deliver an impact blow from said hammer member through said roller impact element to said impact receiving jaw.

4. A rotary impact tool comprising, in combination:

a housing, a motor mounted in said housing,

a centrally located output shaft having two impact receiving jaws radially disposed on its periphery, means rotatably mounting said output shaft to said housing,

a ring-like cage member driven by said motor surrounding said impact receiving jaws and journalled on said output shaft, said cage member having two axially extending slots through its wall,

two roller elements, one mounted in each of said two slots in said cage member with their axes parallel to the axis of the output shaft but displaced radially therefrom, the diameters of said roller elements being such that they extend radially beyond the periphery of said cage member,

a ring-like hammer member surrounding said cage member and journalled thereon, said hammer member having two axially extending grooves in its bore to loosely accommodate the portions of said roller elements beyond the periphery of said cage member causing said cage member and said hammer member to rotate essentially in unison but allowing limited relative rotary motion therebetween, and centrifugal means mounted between said cage member and said hammer member operative periodically during rotation to cause said hammer member to rotate forward ahead of said cage member, said two axially extending grooves being spaced and shaped so that the two roller elements are forced inwardly by the forward motion of the hammer ahead of the cage member into the path of the impact receiving jaws to transmit an impact blow from said hammer member through said roller elements to said impact receiving jaws.

5. A rotary impact tool comprising, in combination:

a housing, a motor mounted in said housing,

a centrally located output shaft having an impact receiving jaw radially disposed on its periphery,

means rotatably mounting said output shaft to said housing,

a slotted cage member journalled on said output shaft and surrounding said impact receiving jaw,

a driving connection from said motor to said cage member,

a ring-like hammer member having an axially extending groove therein surrounding said cage member and journalled thereon,

an impact element carried in the slot in said cage member and extending into the groove in said hammer member allowing limited relative rotary motion between the cage member and the hammer member, said groove being shaped so that motion of said hammer member ahead of said cage member forces said impact element into the annular path of said impact receiving jaw,

and centrifugal means mounted between said cage member and said hammer member operative periodically during rotation to cause said hammer member to rotate forward ahead of said cage member thereby to force said impact element radially inward into the annular path of said impact receiving jaw to deliver an impact blow from said hammer member through said impact element to said impact receiving jaw.

6. A rotary impact tool comprising, in combination:

a housing, a motor mounted in said housing,

an output shaft mounted on said housing for rotation and including an impact receiving jaw generally radially disposed on its periphery,

a movable impact element,

a cage member driven by said motor and mounting said impact element adjacent to the output shaft in the vicinity of the impact receiving jaw and radially displaced therefrom to rotate in an orbit like path about the output shaft,

a ring-like hammer member surrounding the orbit of said impact element,

means mounting said hammer member in said housing for rotary motion essentially in unison with said impact element but being capable of limited relative rotary motion in respect thereto,

and centrifugal means mounted between said cage member and said hammer member operative periodically to force the hammer member ahead of the cage member to cause said impact element to move radially inward into the path of said impact receiving jaw in position to contact said impact receiving jaw and transmit an impact blow from said hammer member through said impact element to said impact receiving jaw. 

1. A rotary impact tool comprising, in combination: a housing, a motor mounted in said housing, an output shaft mounted on said housing for rotation and including an impact receiving jaw generally radially disposed on its periphery, an elongated impact element, a cage member driven by said motor and mounting said impact element adjacent to the output shaft in the vicinity of the impact receiving jaw with its axis parallel to the axis of the output shaft and radially displaced therefrom to rotate in an orbit-like path about the output shaft, a ring-like hammer member surrounding the orbit of said impact element, means mounting said hammer member in said housing for rotary motion essentially in unison with said impact element but being capable of limited relative rotary motion in respect thereto, and cenTrifugal means mounted between said cage member and said hammer member operative periodically to force the hammer member ahead of the cage member to cause said impact element to move radially inward into the path of said impact receiving jaw in position to contact said impact receiving jaw and transmit an impact blow from said hammer member transversely through said impact element to said impact receiving jaw.
 2. A rotary impact tool comprising, in combination: a housing, a motor mounted in said housing, output shaft means mounted on said housing for rotation and including an impact receiving jaw radially disposed on its periphery, a generally cylindrical roller impact element, a cage member driven by said motor mounting said roller impact element adjacent to the impact receiving jaw with its axis parallel to the axis of the output shaft and radially displaced therefrom to rotate in an orbit about the output shaft, a ring-like hammer member surrounding the orbit of said roller impact element, means mounting said hammer member in said housing for rotary motion essentially in unison with said roller impact element but being capable of limited relative motion in respect thereto, and centrifugal means mounted in and driven by said cage member periodically to force said hammer member forward ahead of the cage member without applying torque to the anvil to cause said impact element to move radially inward to contact said impact receiving jaw and transmit an impact blow from said hammer member transversely through said impact element to said impact receiving jaw.
 3. A rotary impact tool, comprising, in combination: a housing, a motor having a motor drive shaft mounted in said housing, a centrally located output shaft including an impact receiving jaw, means rotatably mounting said output shaft in said housing, a cage member having slot means therein, means mounting said cage member around said output shaft at the location of said impact receiving jaw, means connecting said motor drive shaft to said cage member to rotate said cage member as said motor and motor drive shaft rotate, a ring-like hammer member having longitudinal groove means in its bore, means co-axially mounting said hammer around said cage member and said output shaft for rotation with and in respect to said cage member and said output shaft, a generally cylindrical roller impact element mounted in said slot means in said cage member and extending radially through said slot means from said output shaft into said groove in said hammer member and with its axis parallel to the axis of said output shaft, the roller impact element allowing limited relative rotary motion between said cage member and said hammer member, and centrifugal means mounted between said cage member and said hammer member operative periodically during rotation to cause said hammer member to rotate forward ahead of said cage member, thereby to force said roller impact element radially inward into the annular path of said impact receiving jaw to deliver an impact blow from said hammer member through said roller impact element to said impact receiving jaw.
 4. A rotary impact tool comprising, in combination: a housing, a motor mounted in said housing, a centrally located output shaft having two impact receiving jaws radially disposed on its periphery, means rotatably mounting said output shaft to said housing, a ring-like cage member driven by said motor surrounding said impact receiving jaws and journalled on said output shaft, said cage member having two axially extending slots through its wall, two roller elements, one mounted in each of said two slots in said cage member with their axes parallel to the axis of the output shaft but displaced radially therefrom, the diameters of said roller elements being such that they extend radially beyond the periphery of said cage member, a ring-like hammer member surrounding said cage member and Journalled thereon, said hammer member having two axially extending grooves in its bore to loosely accommodate the portions of said roller elements beyond the periphery of said cage member causing said cage member and said hammer member to rotate essentially in unison but allowing limited relative rotary motion therebetween, and centrifugal means mounted between said cage member and said hammer member operative periodically during rotation to cause said hammer member to rotate forward ahead of said cage member, said two axially extending grooves being spaced and shaped so that the two roller elements are forced inwardly by the forward motion of the hammer ahead of the cage member into the path of the impact receiving jaws to transmit an impact blow from said hammer member through said roller elements to said impact receiving jaws.
 5. A rotary impact tool comprising, in combination: a housing, a motor mounted in said housing, a centrally located output shaft having an impact receiving jaw radially disposed on its periphery, means rotatably mounting said output shaft to said housing, a slotted cage member journalled on said output shaft and surrounding said impact receiving jaw, a driving connection from said motor to said cage member, a ring-like hammer member having an axially extending groove therein surrounding said cage member and journalled thereon, an impact element carried in the slot in said cage member and extending into the groove in said hammer member allowing limited relative rotary motion between the cage member and the hammer member, said groove being shaped so that motion of said hammer member ahead of said cage member forces said impact element into the annular path of said impact receiving jaw, and centrifugal means mounted between said cage member and said hammer member operative periodically during rotation to cause said hammer member to rotate forward ahead of said cage member thereby to force said impact element radially inward into the annular path of said impact receiving jaw to deliver an impact blow from said hammer member through said impact element to said impact receiving jaw.
 6. A rotary impact tool comprising, in combination: a housing, a motor mounted in said housing, an output shaft mounted on said housing for rotation and including an impact receiving jaw generally radially disposed on its periphery, a movable impact element, a cage member driven by said motor and mounting said impact element adjacent to the output shaft in the vicinity of the impact receiving jaw and radially displaced therefrom to rotate in an orbit like path about the output shaft, a ring-like hammer member surrounding the orbit of said impact element, means mounting said hammer member in said housing for rotary motion essentially in unison with said impact element but being capable of limited relative rotary motion in respect thereto, and centrifugal means mounted between said cage member and said hammer member operative periodically to force the hammer member ahead of the cage member to cause said impact element to move radially inward into the path of said impact receiving jaw in position to contact said impact receiving jaw and transmit an impact blow from said hammer member through said impact element to said impact receiving jaw. 